AI Matters
Why it matters
Security researcher builds self-spreading worm targeting Microsoft Copilot
The Decoder A security researcher built a self-spreading worm that hides inside Word docs and hijacks Microsoft Copilot
A researcher demonstrated a worm-like attack that uses invisible prompt injections in Word documents to automatically hijack Microsoft Copilot and spread to other files.
Why it matters
This vulnerability shows how hidden prompts in shared documents can silently hijack your AI assistant to compromise files without your knowledge.
Latest brief · Aug 1, 2026